The first basic law of human stupidity asserts without ambiguity that: Always and inevitably everyone underestimates the number of stupid individuals in circulation.
The probability that a certain person be stupid is independent of any other characteristic of that person.
A stupid person is a person who causes losses to another person or to a group of persons while himself deriving no gain and even possibly incurring losses.
Non-stupid people always underestimate the damaging power of stupid individuals. In particular non-stupid people constantly forget that at all times and places and under any circumstances to deal and/or associate with stupid people always turns out to be a costly mistake.
A stupid person is the most dangerous type of person.
The corollary of the Law is that:
A stupid person is more dangerous than a bandit.
This is cute but I have seen this kind of stuff too often to discount it completely.
Sturgeon's Law and the Perato Principle reinforce each other here.
It didn't take me long into my engineering career to figure out that trying for foolproof was an impossible task. They are just so ingenious.
I found that striving for fool-resistance was an achievable goal. At my first job out of college at one point I wrote a program to take the list of battery plates and how many there were and sorted them into batteries. They were figuring them out by hand and having lots of leftover plates.
Each battery could hold a certain number of plates and the total weight needed to be within a particular percentage. This was not a hard exercise though it took a few passes to minimize waste.
The real work came in formating the output so the workers could easily and quickly understand which plates from which bin when into which battery. Eventually each battery became its own page with a page for leftover plates at the end that was specifically labeled as leftover plates.
There is also a difference between stupidity and ignorance. People who are ignorant, don't know something. Stupid people don't WANT to know something and that is a very big difference.
Ignorance is curable, stupidity well...